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| Home > Publications database > The Jig-saw puzzle of crystal structures : alloys, superconducting oxides, semiconductors, ionic conductors, surface adsorbates and magnetic structures |
| Home > Publications database > The Jig-saw puzzle of crystal structures : alloys, superconducting oxides, semiconductors, ionic conductors, surface adsorbates and magnetic structures |
| Book | PreJuSER-62909 |
;
2000
Forschungszentrum, Zentralbibliothek
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/20578
Report No.: Juel-3732
Abstract: The crystal structures of ordered bcc, fcc or primitive cubic alloys AXBy and related NaCl, ZnS or CaF2 derivative structures are characterized by the self-coordination numbers T1, T2 of the A atoms with A atoms. Structures with identical T1 , T2 values for all A atoms are at the corners of T1 , T2 structure maps and can be analyzed for attractive or repulsive interactions of A atoms. Most observed structures are at the borders of the structure map and can be obtained by different combinations of structural units . The combination mechanisms explain e.g. the shear structures of CuAu II or Nb 205 and the occurrence of vacancies in NaC1 related structures like NbO . Many other ordered structures like magnetic ordering, adatoms an metal surfaces, colloids and Clusters are analyzed by the same method . The very large numbers of possible structures are reduced to a smaller number of structures at the borders of the structure maps, which are stabilized by enthalpy. The other structures are stabilized by entropy. The T1 , T2 values of DNA sequences in different areas of the structure map are related with the evolution
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